Power supply device and vehicle including the same

ABSTRACT

A secondary battery includes an electrode body, an outer can, a sealing plate, electrode terminals, and a current interrupt device. The electrode terminals includes a first electrode terminal and a second electrode terminal, and are electrically connected to the electrode body through a collector member. The current interrupt device includes a short-circuit part that short-circuits the battery when the internal pressure exceeds a set pressure, and a fuse part disposed in the collector member. The fuse part is disposed close to an upper end corner portion serving as a boundary portion between an upper surface and a side surface of the secondary battery. A binding member includes a protective cover portion that covers the upper end corner portion of the secondary battery, and the protective cover portion includes an upper-surface covering part and a side-surface covering part.

TECHNICAL FIELD

The present invention relates to a power supply device in which aplurality of secondary batteries capable of charging and discharging arestacked, and to a vehicle including the power supply device.

BACKGROUND ART

In a power supply device for a vehicle, multiple secondary batteriescapable of charging and discharging are connected in series into abattery block, and the output voltage of the battery block is set highto increase power to be supplied to a motor for running the vehicle.This power supply device is discharged by supplying power to the motorin a running state of the vehicle, and is charged by a power generatorin regenerative braking of the vehicle. The discharging current of thebatteries specifies the driving torque of the motor, and the chargingcurrent of the batteries specifies the braking force for regenerativebraking. Therefore, it is necessary to increase the discharging currentof the batteries in order to increase the driving torque of the motorfor accelerating the vehicle, and it is necessary to charge thebatteries with a large current in order to increase regenerative brakingof the vehicle. Accordingly, the batteries in the power supply devicefor the vehicle are discharged or charged with a large current. Toimprove safety in discharging and charging the batteries with a largecurrent, there has been developed a battery including a mechanism thatinterrupts the current when the internal pressure of the batteryabnormally increases, that is, a current interrupt device.

As a battery including such a current interrupt device, for example,there has been proposed a secondary battery including a device thatinterrupts the current by fusing a contained fuse part when the internalpressure of the battery exceeds a set pressure (see PTL 1). Asillustrated in FIG. 14, this secondary battery 101 includes an electrodebody 115, a collector plate 116 connected to the electrode body 115, anouter can 111 that contains the electrode body 115, a sealing plate 112that hermetically seals the outer can 111, an inverting plate 122 havingan edge connected to the sealing plate 112 and made of a conductivematerial, and a connection plate 123 insulated from the sealing plate112 by an insulating member 124 and having a different polarity. Thecollector plate 116 has a fuse part 121 to be melted by heat of anovercurrent. The inverting plate 122 normally bulges toward an innerregion of the outer can 111, and inverts when the pressure in thebattery exceeds the set pressure. In the secondary battery 101, when theinternal pressure of the outer can 111 rises, the inverting plate 122inverts and comes into contact with the connection plate 123, and ashort circuit is made inside the secondary battery 101. At this time,inside the battery, the fuse part 121 provided in the collector plate116 is melted by heat, and this breaks the electrical connection betweenelectrode terminals of the battery and the electrode body 115.

CITATION LIST Patent Literature

PTL 1: Japanese Published Unexamined Patent Application No. 2012-195278

SUMMARY OF INVENTION Technical Problem

The current can be reliably interrupted by fusing of the fuse partcontained in the secondary battery by completely fusing and cutting offthe fuse part. In an actual secondary battery, however, it is difficultto completely fuse the fuse part in a limited narrow space inside thebattery. It is conceivable that a spark will occur at the time of fusingand that a spark will be caused by reconduction resulting from thecontact between fused portions.

Particularly when the fuse part is fused in the vehicular power supplydevice, the current is interrupted and motor driving cannot beperformed, but, for example, a hybrid car can run by using the engine.However, it is conceivable that, if engine driving is performed in thisstate, the fused portions may come into contact with each other insidethe secondary battery and a spark may be caused by reconduction. Inparticular, in the secondary battery mounted in the vehicle, vibrationdue to driving of the vehicle cannot be completely removed. It isconceivable that the fused portions may be brought into contact witheach other by external vibration and a spark may be easily caused byreconduction. From these, the present inventors considered that, in thesecondary battery including the current interrupt device forinterrupting the current by fusing the fuse part, the occurrence of thespark at the time of fusing and reconduction could not be completelyavoided and that it was necessary to take measures to prevent scatteringof the spark to the outside of the secondary battery.

The present invention has been made in view of these problems of therelated art. An object of the invention is to provide a power supplydevice that can effectively prevent a spark from scattering to theoutside of a secondary battery even if the spark occurs at fusedportions and damages an outer can when a fuse part contained in thesecond battery is fused and reconducted, and a vehicle including thepower supply device.

Solution to Problem and Advantageous Effects of Invention

To achieve the above object, a power supply device according to thepresent invention includes a battery stack in which a plurality ofsecondary batteries are stacked, and a binding member that binds thebattery stack. Each of the secondary batteries includes an electrodebody having a positive electrode and a negative electrode, an outer canhaving an opening and shaped like a bottomed cylinder to contain theelectrode body, a sealing plate that closes the opening of the outercan, a pair of electrode terminals disposed on the sealing plate, and acurrent interrupt device that operates when an internal pressure of thesecondary battery exceeds a set pressure. The pair of electrodeterminals include a first electrode terminal insulated from the sealingplate and a second electrode terminal electrically connected to thesealing plate, and are electrically connected to the electrode bodythrough a collector member inside the secondary battery. The currentinterrupt device includes a short-circuit part that short-circuits thefirst electrode terminal and the sealing plate when the internalpressure of the secondary battery exceeds the set pressure, and a fusepart provided in the collector member. The fuse part is disposed closeto an upper end corner portion serving as a boundary portion between anupper surface and a side surface of the secondary battery, and is fusedby an overcurrent in a short-circuit state of the short-circuit part.The binding member includes a protective cover portion located on eachside of the battery stack to cover the upper end corner portion of thesecondary battery. The protective cover portion includes anupper-surface covering part that covers an upper surface of the upperend corner portion and a side-surface covering part that covers a sidesurface of the upper end corner portion.

In this description, the up-down direction of the secondary battery isspecified in the drawings. The side surface of the second battery refersto a narrow surface on each side of a battery stack in which a pluralityof secondary batteries are stacked with wide principal surfaces opposedto each other.

The present invention is effective particularly when the fuse part islocated in a region at a direct distance of 2 cm or less from the upperend corner portion. Further, the present invention is more effectivewhen the fuse part is located in a region at a direct distance of 1 cmor less from the upper end corner portion. Preferably, the collectormember has a platelike portion, and the fuse part is constituted by aportion having a small cross-sectional area obtained by forming anopening in the platelike portion. The present invention is moreeffective when the fuse part is located in a region of the collectormember between the sealing plate and the electrode body. Further, thepresent invention is more effective when the platelike portion of thecollector member having the fuse part is located parallel to the sealingplate.

According to the power supply device having the above-describedstructure, the fuse part in the current, interrupt device is locatedclose to the upper end corner portion of the secondary battery, and thebinding member that binds the battery stack has the protective coverportion that covers the upper end corner portion of the secondarybattery. Hence, even if a spark occurs at fused portions and damages theouter can during fusing and reconduction of the contained fuse part, thespark can be effectively prevented from scattering to the outside of thesecond battery. In particular, since the protective cover portionincludes the upper-surface covering part that covers the upper surfaceof the upper end corner portion and the side-surface covering part thatcovers the side surface, the protective cover portion can reliably coverthe upper end corner portion of the secondary battery and caneffectively prevent scattering of the spark from the upper end cornerportion.

In the power supply device of the present invention, the binding membercan be a bind bar formed by bending a metal plate having a predeterminedthickness. According to the above structure, the binding member can beeasily produced at low cost by bending the metal plate.

In the power supply device of the present invention, an insulatingmember can be provided on an inner surface of the bind bar. According tothe above structure, while the binding member is the metal plate, aportion thereof opposed to the battery stack can be insulated and safelyused.

In the power supply device of the present invention, the bind bar caninclude an upper bind bar that covers an upper portion of a side surfaceof the battery stack and a lower bind bar that covers a lower portion ofthe side surface of the battery stack, and the upper bind bar can alsofunction as the protective cover portion. According to the structure,since the battery stack is connected by four bind bars, four corners ofthe battery stack can be bound in an ideal state by the bind bars.

In the power supply device of the present invention, the bind bar canhave a body portion opposed to a side surface of the battery stack, andthe body portion can cover the entire side surface of the battery stack.According to the above structure, the mechanical strength can beincreased by widening the bind bar opposed to the side surface of thebattery stack. Moreover, since the side surface of the battery stack isentirely covered, the spark can be reliably prevented from scatteringtoward the side surface of the battery stack.

In the power supply device of the present invention, the bind bar canhave a body portion opposed to a side surface of the battery stack, andthe body portion can have an open window. According to the abovestructure, the weight of the bind bar opposed to the side surface of thebattery stack can be reduced, and heat can be effectively dissipated byexposing the side surface of the secondary battery from the open window.

In the power supply device of the present invention, the bind bar canhave a horizontal portion that covers at least a part of a bottomsurface of the battery stack. According to the above structure, since atleast a part of the bottom surface of the battery stack is covered withthe horizontal portion, a plurality of stacked secondary batteries canbe bound while positioning the bottom surfaces of the secondarybatteries, and the vibration-resistant strength can be further increasedby further suppressing the relative movement in the up-down direction.

A vehicle according to the present invention includes any of theabove-described power supply devices.

According to the vehicle having the above-described structure, while thepower supply device having a plurality of secondary batteries is mountedin the vehicle, the binding member that, binds the battery stack isprovided with the protective cover portion that covers the upper endcorner portion of each of the secondary batteries. Hence, even if aspark occurs at fused portions and damages the outer can at the time offusing and reconduction of the contained fuse part, the spark can beeffectively prevented from scattering to the outside of the secondbattery. In particular, since the protective cover portion of thebinding member includes the upper-surface covering part that covers theupper surface of the upper-end corner portion and the side-surfacecovering part that covers the side surface, the protective cover portioncan reliably cover the upper end corner portion of the secondary batteryand can effectively prevent the spark from scattering from the upper endcorner portion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of a power supply deviceaccording to a first embodiment of the present, invention.

FIG. 2 is a perspective view of an assembled battery in the power supplydevice illustrated in FIG. 1.

FIG. 3 is an exploded perspective view of the assembled batteryillustrated in FIG. 2.

FIG. 4 is a vertical cross-sectional view of the assembled batteryillustrated in FIG. 2, and illustrates an internal structure of asecondary battery.

FIG. 5 is a cross-sectional view illustrating an operating state of acurrent interrupt device in the secondary battery illustrated in FIG. 4.

FIG. 6 is an enlarged perspective view of a fuse part provided in acollector member.

FIG. 7 is an enlarged perspective view of another example of the fusepart.

FIG. 8 is a schematic sectional view of an assembled battery accordingto a second embodiment of the present invention.

FIG. 9 is a vertical cross-sectional view of the assembled battery ofFIG. 8.

FIG. 10 is a vertical cross-sectional view of an assembled batteryaccording to a third embodiment of the present invention.

FIG. 11 is a vertical cross-sectional view of an assembled batteryaccording to a fourth embodiment of the present invention.

FIG. 12 is a perspective view of another example of binding members.

FIG. 13 is a perspective view of a further example of the bindingmembers.

FIG. 14 is a schematic sectional view illustrating an example of acurrent interrupt device in a conventional secondary battery.

DESCRIPTION OF EMBODIMENTS First Embodiment

FIGS. 1 to 5 illustrate a power supply device 100 according to a firstembodiment of the present invention. The power supply device 100illustrated in these figures is an example of a vehicle-mounted powersupply device. Specifically, the power supply device 100 is mainlymounted in an electrically driven vehicle such as a hybrid car or anelectric car, and is used as a power supply that supplies power to arunning motor of the vehicle to run the vehicle. The power supply deviceof the present invention can be used in electrically driven vehiclesother than the hybrid car and the electric car, and can also be used forapplications requiring large output other than the electrically drivenvehicles.

(Power Supply Device 100)

As illustrated in an exploded perspective view of FIG. 1, the powersupply device 100 has an outer shape like a box having a rectangularupper surface. A box-shaped outer case 70 of the power supply device 100is divided to store a plurality of assembled batteries 10 therein. Theouter case 70 includes a lower case 71, an upper case 72, and end faceplates 73 connected to both ends of each of the lower case 71 and theupper case 72. The end face plates 73 are connected to both ends of eachof the lower case 71 and the upper case 72 to close both ends of theouter case 70. The upper case 72 has flanges 74 projecting outward, andis fixed to the lower case 71 by bolts and nuts through screw holesopening in the flanges 74. The screw holes of the flanges 74 can also beused to fix the power supply device 100. For example, the power supplydevice 100 is fixed to the vehicle by screwing using the screw holes.

The assembled batteries 10 are fixed at determined positions inside theouter case 70. In the example of FIG. 1, two assembled batteries 10arranged in the longitudinal direction and two assembled batteries 10arranged in the lateral direction, that is, a total of four assembledbatteries 10 are stored in the outer case 70. The number and layout ofthe assembled batteries are not limited to those of this example. Forexample, one assembled battery may be stored in the outer case.

(Assembled Batteries 10)

As illustrated in FIGS. 2 and 3, each assembled battery 10 includes aplurality of secondary batteries 1, separators 2 interposed betweensurfaces of the plurality of stacked secondary batteries 1 to isolatethe secondary batteries 1, a pair of end plates 3 disposed on end facesof a battery stack 5 in a stacking direction in which the plurality ofsecondary batteries 1 and the separators 2 are alternately stacked, anda plurality of metallic binding members 4 disposed on a side surface oran upper surface of the battery stack 5 to bind the end plates 3. Theassembled battery 10 is also fixed to the lower case 71. For example,bottom surfaces of the secondary batteries 1 are fixed onto the lowercase 71 by adhesion using an adhesive.

The lower case 71 also functions as a cooling plate that cools thebattery stack 5. That is, heat generated by the secondary batteries 1 isthermally conducted to the lower case 71 to promote heat dissipation bythermally bonding the bottom surfaces of the secondary batteries 1 tothe lower case 71. A cooling pipe for circulating a refrigerant may bedisposed on a lower surface or an inner side of the lower case 71. Theseparators 2 may have grooves through which a cooling gas is passed tocool the secondary batteries 1.

(Battery Stack 5)

In each assembled battery 10, a plurality of secondary batteries 1 arestacked with insulating separators 2 interposed therebetween to form abattery stack 5, a pair of end plates 3 are disposed on both end facesof the battery stack 5, and the pair of end plates 3 are connected bybinding members 4. In the assembled battery 10 illustrated in thesefigures, the separators 2 for insulating the adjacent secondarybatteries 1 are interposed between stacking surfaces of the secondarybatteries 1, and the secondary batteries 1 and the separators 2 arealternately stacked to constitute the battery stack 5.

In the assembled battery, the separators do not always need to beinterposed between the secondary batteries. For example, the separatorscan be omitted by insulating the adjacent second batteries by means of amethod of forming outer cans of the secondary batteries of an insulatingmaterial such as resin, or a method of covering outer peripheries of theouter cans of the secondary batteries with heat-shrinkage tubes,insulating sheets, or an insulating paint. Particularly in a structurethat adopts a method of cooling the battery stack through a cooling pipecooled by, for example, a refrigerant, without using an air coolingmethod of cooling the secondary batteries by forcibly blowing coolingair between the secondary batteries, it is not always necessary tointerpose the separators between the secondary batteries.

(Secondary Batteries 1)

As illustrated in FIG. 3, the secondary batteries 1 are square batterieshaving an outer shape that is smaller in thickness than in width. Thesecondary batteries 1 are chargeable and dischargeable batteries such aslithium-ion secondary batteries, nickel-hydrogen secondary batteries, ornickel-cadmium secondary batteries. Particularly when lithium-ionsecondary batteries are used as the secondary batteries 1, it ispossible to increase the charging capacity with respect to the totalvolume or mass of the secondary batteries.

As illustrated in FIG. 4, each of the secondary batteries 1 includes anelectrode body 15 having a positive electrode and a negative electrode,an outer can 11 shaped like a bottomed cylinder having an opening in onesurface and containing the electrode body 15, a sealing plate 12 thatcloses the opening of the outer can 11, and a pair of electrodeterminals 13 disposed at both ends of the sealing plate 12. The positiveelectrode and the negative electrode of the electrode body 15 arehelically wound with a separator interposed therebetween, are pressed toa predetermined thickness, and are inserted in the outer can 11. Theouter can 11 is shaped like a rectangular cylinder having a closedbottom and both opposed wide surfaces, and is open upward in the figure.The outer can 11 having this shape is produced by pressing a metal platemade of, for example, aluminum or an aluminum alloy. The opening of theouter can 11 is closed by laser-welding the flat sealing plate 12 formedby pressing a metal plate.

The sealing plate 12 has a gas discharge valve 14 between the pair ofelectrode terminals 13. The gas discharge valve 14 opens to dischargeinner gas when the internal pressure of the outer can 11 rises to apressure higher than or equal to a predetermined pressure. By openingthe gas discharge valve 14, the rise of the internal pressure of theouter can 11 can be suppressed. The gas discharge valve 14 is preferablydisposed at almost, the longitudinal center of the sealing plate 12.Thus, even if the adjacent secondary batteries 1 are stacked while beingalternately reversed in the lateral direction, the gas discharge valve14 can be always aligned with the center of the sealing plate 12.Further, the sealing plate 12 has a liquid injection portion 19 adjacentto the gas discharge valve and allowing injection of an electrolytetherethrough. The secondary battery 1 is produced by inserting theelectrode body 15 in the outer can 11, hermetically sealing the openingof the outer can 11 with the sealing plate 12, and then injecting anelectrolyte (not illustrated) from the liquid injection portion 19.

The pair of electrode terminals 13 includes a first electrode terminal13A insulated from the sealing plate 12 and a second electrode terminal13B electrically connected to the sealing plate 12. The pair ofelectrode terminals 13 are fixed to determined positions on the sealingplate 12 with gaskets 17 interposed therebetween. The first electrodeterminal 13A is connected to the sealing plate 12 in an insulated statewith the gasket 17 interposed therebetween. The second electrodeterminal 13B is connected to the sealing plate 12 with the gasket 17interposed therebetween, and is electrically connected to an uppersurface side of the sealing plate 12 with a metallic fixed member 18,which is fixed to the second electrode terminal 13B, interposedtherebetween. Inside the secondary battery 1, the positive and negativeelectrode terminals 13 fixed to the sealing plate 12 are electricallyconnected to the electrode body 15 with collector members 16 interposedtherebetween. In the secondary battery 1, the second electrode terminal13B connected to the sealing plate 12 and the outer can 11 serves as apositive terminal, and the first electrode terminal 13A serves as anegative terminal.

(Current Interrupt Device 7)

To avoid a thermal runaway, for example, due to overcharging, each ofthe secondary batteries 1 includes a current interrupt device 7 thatbreaks electric connection between the electrode body 15 and the secondelectrode terminal 13B in response to the rise of the internal pressureof the outer can 11. The illustrated current interrupt device 7 includesa short-circuit part 20 that short-circuits the first electrode terminal13A and the sealing plate 12 when the internal pressure of the secondarybattery 1 exceeds the set pressure, and a fuse part 21 provided in thecollector member 16 connected to the second electrode terminal 13B. Inthe current interrupt device 7, in a state in which the internalpressure of the battery exceeds the set pressure and the short-circuitpart 20 makes a short circuit, the fuse part 21 is fused by anovercurrent flowing through the fuse part 21. As a result, theelectrical connection between the electrode body 15 and the secondelectrode terminal 13B is broken and the current is interrupted.

(Short-Circuit Part 20)

When the internal pressure of the secondary battery 1 exceeds the setpressure, for example, owing to overcharging, the short-circuit part 20serves to induce a short circuit so that a large current flows throughthe fuse part 21. The short-circuit part 20 illustrated in FIG. 3includes an inverting plate 22 fixed to the sealing plate 12 and made ofa conductive material and a metallic connection plate 23 disposed on theupper side of the sealing plate 12 to be opposed to the inverting plate22.

(Inverting Plate 22)

As illustrated in FIG. 4, the inverting plate 22 is attached at ashort-circuit hole 12A opening in the sealing plate 12, for example, bywelding. An outer peripheral edge portion of the inverting plate 22 iselectrically connected to the sealing plate 12, and a center portion ofthe inverting plate 22 is curved to project toward the inside of theouter can 11. When overcharging occurs in the secondary battery 1 andthe internal pressure of the secondary battery 1 exceeds the setpressure, as illustrated in FIG. 5, the inverting plate 22 inverts andbulges upward, that is projects in a direction apart from the electrodebody 15 and comes into contact with the connection plate 23, so that ashort-circuit is induced.

While one inverting plate 22 is provided in the short-circuit part 20 ofthis example, a plurality of inverting plates may be stacked. In ashort-circuit part including a plurality of stacked inverting plates,when the inverting plates are made different in thickness and setinverting pressure, it is possible to more smoothly respond to the riseof the internal pressure of the battery and to continue the fusefunction of the fuse part while maintaining a short circuit of one ofthe inverting plates even when the other inverting plate is fused byheat.

The connection plate 23 is disposed on the upper surface of the sealingplate 12 with an insulating portion 24 interposed therebetween, and isconnected to the sealing plate 12 in an insulated state. The connectionplate 23 is electrically connected to the first electrode terminal 13A.Specifically, the first electrode terminal 13A is passed through a holeopening in a part of the connection plate 23, and the connection plate23 and the first electrode terminal 13A are electrically connectedthrough the fixed member 18 fixed to the first electrode terminal 13A onthe upper side of the connection plate 23.

(Fuse Part 21)

The fuse part 21 is to be fused and cut off by heat generated by anovercurrent flowing through the battery in a short-circuit state of theshort-circuit part 20, and is disposed in a conduction path of thecurrent at the time of a short circuit. The fuse part 21 illustrated inFIG. 3 is disposed in the collector member 16 connected to the secondelectrode terminal 13B. The fuse part 21 provided in the collectormember 16 is to be fused by an overcurrent flowing through the collectormember 16 in the short-circuit state of the short-circuit part 20.

The fuse part 21 illustrated in FIG. 3 is constituted by a fuse hole 21Aopening in the collector member 16, and specifically, is constituted bya connecting portion 21B on both sides of the fuse hole 21A opening in aplatelike portion 16A of the collector member 16, as illustrated in FIG.6. The connecting portion 21B has a cross-sectional area that is reducedby the opening of the fuse hole 21A, and the electric resistance thereoflocally increases. Thus, the connecting portion 21B functions as a fusethat interrupts the current by being fused by heat generated by a largecurrent flowing in the short circuit of the secondary battery 1. In thecollector member 16 illustrated in FIG. 6, one fuse hole 21A is open inthe platelike portion 16A, and the connecting portion 21B is located onboth sides of the fuse hole 21A. In the collector member 16, asillustrated in FIG. 7, a plurality of (two in FIG. 7) fuse holes 21A canopen in the platelike portion 16A and a connecting portion 21B can belocated in a portion between the fuse holes 21A and in both sideportions of the platelike portion 16A. While the planar shape of thefuse hole 21A is elliptic or circular in FIGS. 6 and 7, the shape, suchas an oval shape, a rectangular shape, a polygonal shape, an arc shape,or a slit shape, and layout of the fuse hole 21A can be changedvariously. Although not illustrated, in the fuse part, cutouts can beprovided in both side portions of the platelike portion and a narrowportion in a center portion of the platelike portion can serve as aconnecting portion, a cutout can be provided in one side portion of theplatelike portion and the other remaining side portion can serve as aconnecting portion, or a cutout can be provided on a side portion of theplatelike portion and a fuse hole can be provided in a center portion ofthe platelike portion so that an obtained narrow portion serves as aconnecting portion.

In the above-described fuse part 21, the connecting portion 21B is fusedand cut off in the region where the fuse hole 21A or the cutout areprovided. This electrically separates the platelike portion 16A of thecollector member 16 and interrupts the current. As illustrated in FIG.3, the fuse part 21 is disposed in a region on an upper side of theelectrode body 15 stored in the outer can 11 and on an outer side of theelectrode terminal 13. That is, the fuse part 21 is disposed close to anupper end corner portion 1T serving as a boundary portion between theupper surface and the side surface of the secondary battery 1.

The fuse part 21 is preferably obtained by forming an opening in theplatelike portion 16A of the collector member 16. Further, the thicknessof the sealing plate 12 is preferably more than or equal to double thethickness of the platelike portion 16A of the collector member 16.

In the current interrupt device 7 illustrated in FIG. 3, the fuse part21 is provided in the collector member 16 connected to the secondelectrode terminal 13B. This structure can reduce the adverse effect onthe short-circuit part 20 resulting from the spark caused during fusingand reconduction of the fuse part 21 because the short-circuit part 20and the fuse part 21 are arranged apart from each other. However, thefuse part, can be provided in the collector member connected to thefirst electrode terminal.

In the above-described current interrupt device 7, when the internalpressure of the secondary battery 1 becomes higher than or equal to theset pressure, as illustrated in FIG. 5, the inverting plate 22 is pushedup by the internal pressure, and is thereby deformed and inverted. Whenthe inverting plate 22 is inverted and comes into contact with theconnection plate 23, the inverting plate 22 and the connection plate 23are conductively connected and the short-circuit part 20 makes a shortcircuit. When the short-circuit part 20 makes the short circuit, a largecurrent flows inside the secondary battery 1 along a path shown by abold line arrow in FIG. 5. At this time, the fuse part 21 in theconduction path is heated, melted, and cut off by the Joule heat due tothe large current, and this interrupts the current. Thus, when theinternal pressure of the second battery 1 abnormally rises, the currentflowing through the secondary battery 1 is interrupted to ensure safetyof the secondary battery 1.

As illustrated in FIG. 3, the above-described secondary batteries 1 arestacked into the battery stack 5 in such a posture that wide surfacesserving as principal surfaces 1X are opposed to each other and thatupper surfaces 1A thereof are flush with one another and side surfaces1B thereof are flush with one another. The plurality of secondarybatteries 1 stacked to constitute the battery stack 5 are connected inseries with the adjacent positive and negative electrode terminals 13connected by bus bars 6. When the adjacent secondary batteries 1 areconnected in series, the output voltage and output of the assembledbattery 10 can be increased. In the assembled battery, however, theadjacent secondary batteries can be connected in parallel or can beconnected in a multi-serial parallel manner by combination of serialconnection and parallel connection.

In the assembled battery 10 in which the secondary batteries 1 areconnected in series, as illustrated in the perspective views of FIGS. 2and 3, the secondary batteries 1 are stacked in such a posture that thepositive and negative electrode terminals 13 of the adjacent secondarybatteries 1 are close to each other, in other words, in such a posturethat the secondary batteries 1 are alternately reversed in the lateraldirection. This can reduce the size of the bus bars 6 that connect theelectrode terminals 13. In this structure, the fuse parts 21 containedin the secondary batteries 1 are different in position between theadjacent secondary batteries 1.

(Separators 2)

The secondary batteries 1 are constituted by the metallic outer cans 11.The secondary batteries 1 hold the insulating separators 2 therebetweento prevent a short, circuit between the outer cans 11 of the adjacentsecondary batteries 1. The separators 2 are spacers that allow theadjacent secondary batteries 1 to be stacked while being electricallyand thermally insulated from each other. The separators 2 are made of aninsulating material such as resin, and are disposed between the adjacentsecondary batteries 1 to insulate the adjacent secondary batteries 1.

(End Plates 3)

A pair of end plates 3 are disposed on both end surfaces of the batterystack 5 in which the secondary batteries 1 and the separators 2 arealternately stacked, and the pair of end plates 3 bind the battery stack5. The end plates 3 are made of a material that exhibits a sufficientstrength, for example, metal. The end plates 3 have fixing structures tobe fixed to the lower case 71 illustrated in FIG. 1. Alternatively, theend plates may be made of resin, and further, the resin end plates maybe reinforced by members made of a metal material.

(Binding Members 4)

As illustrated in FIGS. 2 to 5, the binding members 4 are disposed onthe side surfaces and the upper surface of the battery stack 5 with theend plates 3 stacked on both ends, and are each fixed at both ends tothe pair of end plates 3 to bind the battery stack 5. The illustratedbinding members 4 are provided as bind bars 40 each obtained by bendinga metal plate of a predetermined thickness into a predetermined shape.These bind bars 40 can be made of a material having a sufficientstrength, for example, a metal plate of iron, and preferably a steelplate. By thus using the bind bars 40 each formed by bending the metalplate as the binding members 4, the cost can be reduced.

The binding members 4 serving as the bind bars 40 extend in the stackingdirection of the battery stack 5, and are each fixed at. both ends tothe pair of end plates 3. Each of the bind bars 40 has a body portion 41disposed along the side surface of the battery stack 5, and connectingpieces 42 disposed at both ends of the body portion 41 and fixed to theend plates 3. Bind bars 40A illustrated in FIGS. 2 to 5 are disposedopposed to upper portions and lower portions of side surfaces of thebattery stack 5 and the end plates 3. That is, the pair of end plates 3are bound by four bind bars 40A. The four bind bars 40A include twoupper bind bars 40X disposed on the upper portions of the side surfacesof the battery stack 5 and two lower bind bars 40Y disposed on the lowerportions of the side surfaces of the battery stack 5.

Each of the upper bind bars 40X has an L-shaped cross section defined byconnecting pieces 42 at both ends of a body portion 41 of apredetermined width and a horizontal portion 43 at an upper end of thebody portion 41 to cover the upper surface of the battery stack 5. Ineach of the upper bind bars 40X illustrated in FIG. 4, the body portion41 is extended upward and the extended portion is bent onto the uppersurface of the battery stack 5 to form the horizontal portion 43. Thehorizontal portion 43 is bent substantially perpendicularly to the bodyportion 41 to take a horizontal posture along the upper surfaces of thesecondary batteries 1. The horizontal portion 43 of the upper bind bar40X serves as a holding portion for holding the upper surface of thebattery stack 5. As illustrated in FIG. 3, each of the lower bind bars40Y has connecting pieces 42 at both ends of a body portion 41 having apredetermined width.

The connecting pieces 42 at both ends of the body portion 41 are bentperpendicularly to the body portion 41 to be in surface contact withouter side surfaces of the end plates 3. Although not illustrated, bothends of each bind bar 40 are fixed to the end plates 3 by connectorssuch as setscrews, are fixed to the end plates 3 by a retainingstructure, or are fixed to the end plates 3 by bonding or welding. Ineach bind bar 40 illustrated in FIGS. 2 and 3, the connecting pieces 42are formed by bending both ends of the bind bar 40, and can be fixed tothe outer side surfaces of the end plates 3 by the connecting pieces 42.However, the bind bar does not always need to have the connecting piecesat both ends. A bind bar having no connecting piece can be fixed byscrewing connectors, such as setscrews, penetrating both ends of thebind bar into the side surfaces of the end plates or penetrating theconnectors through the end plates in the up-down direction or theright-left direction. This structure can shorten the total length of theassembled battery.

The binding members 4 further include protective cover portions 8 thatcover upper end corner portions 1T at boundaries of the upper surfaces1A and the side surfaces 1B of the secondary batteries 1. The protectivecover portions 8 are disposed to cover the upper end corner portions 1Tof the secondary batteries 1 close to the fuse parts 21 contained in theouter cans 11. In each illustrated secondary battery 1, since the fusepart 21 is provided in the collector member 16 that connects the secondelectrode terminal 13B at the end of the sealing plate 12 and theelectrode body 15, the protective cover portion 8 is disposed to coveran edge where the second electrode terminal 13B is disposed in aconnecting portion between the sealing plate 12 and the outer can 11. Inthe binding member 4 of this example, the upper bind bar 40X alsofunctions as the protective cover portion 8.

The protective cover portion 8 illustrated in FIG. 4 includes anupper-surface covering part 8A that covers an upper surface of the upperend corner portion 1T and a side-surface covering part 8B that covers aside surface of the upper end corner portion 1T. That is, in the upperbind bar 40X illustrated in FIG. 4, the body portion 41 covering theupper portion of the side surface of the battery stack 5 functions asthe side-surface covering part 8B of the protective cover portion 8, andthe horizontal portion 43 covering the upper surface of the batterystack 5 functions as the upper-surface covering part 8A of theprotective cover portion 8.

When a spark occurs inside the secondary battery 1, a portion near thejoint portion between the opening of the outer can 11 and the sealingplate 12 is most subject to breakage. Therefore, the shape and size ofthe protective cover portion 8 are such as to cover a region providednear the upper end corner portion 1T of the secondary battery 1 andincluding at least a welded portion 25 between the opening of the outercan 11 and the edge of the sealing plate 12. In the illustratedsecondary battery 1, the boundary portion is welded at the opening ofthe outer can 11 in a state in which the outer peripheral edge of thesealing plate 12 is fitted inside the edge of the opening of the outercan 11. Therefore, in the secondary battery 1, the welded portion 25between the outer can 11 and the sealing plate 12 is provided on theupper surface of the secondary battery 1. In the protective coverportion 8 illustrated in FIG. 4, the welded portion 25 inside theopening edge of the outer can 11 is covered with the upper-surfacecovering part 8A covering the upper surface of the upper end cornerportion 1T. The upper-surface covering part 8A preferably extends to aposition that is close to the electrode terminal 13, but is out ofcontact with the electrode terminal 13, and covers the upper surface ofthe upper end corner portion 1T. Therefore, a length (S) of thesecondary battery 1 in the width direction, along which theupper-surface covering part 8A covers the upper surface of the upper endcorner portion 1T, is larger than the thickness of the outer can 11 andis 2 mm or more, and preferably 5 mm or more. A length (H) in thevertical direction, along which the side-surface covering part 8B coversthe side surface of the upper end corner portion 1T, is 1 cm or more,and preferably 3 cm or more.

In the secondary battery, however, the welded portion does not alwaysneed to be provided on the upper surface. Although not illustrated, theboundary portion can also be welded in a state in which the outerperipheral edge of the sealing plate is in contact with the opening edgeof the opening of the outer can. In this secondary battery, a weldedportion between the outer can and the sealing plate is provided on anouter peripheral surface (side surface and principal surface) of thesecondary battery along the outer peripheral edge of the sealing plate.In the secondary battery having this structure, the side-surfacecovering part covering the side surface of the upper end corner portioncovers the welded portion outside the opening edge of the outer can.

In the assembled battery 10 in which the plurality of secondarybatteries 1 are connected in series, as described above, the adjacentsecondary batteries 1 are stacked in such a posture to be alternatelyreversed in the lateral direction to connect the adjacent positive andnegative electrode terminals 13 by the bus bars 6 in the shortestdistance. For this reason, the positions of the fuse parts 21 containedin the secondary batteries 1 alternately differ between the adjacentsecondary batteries 1. Therefore, in this assembled battery 10, asillustrated in FIGS. 2 to 4, the protective cover portions 8 aredisposed on both sides of the battery stack 5 to cover the upper endcorner portions 1T of the secondary batteries 1. Thus, in any of thesecondary batteries 1, the upper end corner portion 1T close to the fusepart 21 is covered with the protective cover portion 8. Even if a sparkoccurs inside the battery, the protective cover portion 8 suppressesscattering of the spark to the outside of the battery. This can improvesafety.

(Insulating Member 45)

The assembled battery 10 illustrated in FIG. 4 has insulating members 45on inner surfaces of the bind bars 40. The insulating members 45insulate the metallic bind bars 40 and the outer can 11 of eachsecondary battery 1, and, for example, insulating sheets, insulatingplates, or an insulating paint can be used. In particular, theinsulating members 45 on the inner surfaces of the protective coverportions 8 are each preferably constituted by a sheet material or aplate material made of a heat-resistant or flame-resistant resin, andthis can reduce breakage and adverse effects due to the spark. Theinsulating members 45 are preferably provided all over the innersurfaces of the bind bars 40 to insulate the surfaces opposed to thebattery stack 5. In the illustrated assembled battery 10, the insulatingmembers 45 are disposed on the inner surfaces of the upper bind bars 40Xand the inner surfaces of the lower bind bars 40Y. Some of theseparators 2 disposed between the secondary batteries 1 can alsofunction as the insulating members 45. In the secondary battery in whichthe outer can and the surface of the sealing plate are covered with, forexample, a heat-shrinkage tube, an insulating sheet, or an insulatingpoint, as described above, the insulating members on the inner surfacesof the bind bars can be omitted.

In the above-described embodiment, the binding members 4 are constitutedby four bind bars 40A, the upper bind bars 40X bind the upper portionsof the side surfaces of the battery stack 5, and the lower bind bars 40Ybind the lower portions of the battery stack 5. Although notillustrated, according to this structure, in an air-cooled power supplydevice that cools secondary batteries by forcibly blowing cooling airbetween the secondary batteries, the cooling air can be passed and blownthrough ventilations defined by gaps serving between the upper bind barsand the lower bind bars. However, in the present invention, the bindingmembers 4 on each side of the battery stack 5 can also be constituted byone bind bar 40B.

Second Embodiment

In an assembled battery 10 illustrated in FIGS. 8 and 9, bind bars 40Binclude their respective body portions 41 opposed to side surfaces of abattery stack 5, and the body portions 41 cover the entire side surfacesof the battery stack 5. The illustrated bind bars 40B each have anL-shaped cross section defined by connecting pieces 42 at both ends ofeach of the body portions 41 having such a width as to cover the entireside surfaces of the battery stack 5 and horizontal portions 43 at upperends of the body portions 41 to cover an upper surface of the batterystack 5. The bind bars 40B also function as protective cover portions 8that cover upper end corner portions 1T of secondary batteries 1. Thatis, the body portions 41 covering upper portions of the side surfaces ofthe battery stack 5 function as side-surface covering parts 8B of theprotective cover portions 8, and the horizontal portions 43 covering theupper surface of the battery stack 5 function as upper-surface coveringparts 8A of the protective cover portions 8. Further, the bind bars 40Bhave insulating members 45 all over inner surfaces thereof to cover theentire side surfaces and both end portions of the upper surface of thebattery stack 5. In the bind bars 40B having this structure, the bodyportions 41 opposed to the side surfaces of the battery stack 5 are madewide, and this can increase the mechanical strength. Also, the sidesurfaces of the battery stack 5 are entirely covered, and this canreliably prevent scattering of the spark toward the side surfaces of thebattery stack 5.

Alternatively, the binding members 4 can be configured to cover at leasta part of the bottom surface of the battery stack 5. For example, thebinding members 4 can cover corner portions on the bottom side of thebattery stack 5 by providing horizontal portions 43 at lower ends of thebind bars 40.

Third Embodiment

Bind bars 40C illustrated in FIG. 10 include two upper bind bars 40Xdisposed at corner portions on an upper side of a battery stack 5 andtwo lower bind bars 40Y disposed at corner portions on a lower side ofthe battery stack 5. The upper bind bars 40X each have an L-shaped crosssection defined by connecting pieces 42 at both ends of each of bodyportions 41 having a predetermined width and horizontal portions 43 atupper ends of the body portions 41 to cover the upper surface of thebattery stack 5, similarly to the above-described upper bind bars 40X.The upper bind bars 40X also function as protective cover portions 8.The lower bind bars 40Z each have an L-shaped cross section defined byconnecting pieces 42 at both ends of each of body portions 41 having apredetermined width and horizontal portions 43 at lower ends of the bodyportions 4 to cover a bottom surface of the battery stack 5. Thehorizontal portions 43 are bent substantially perpendicularly to thebody portions 41 to take a horizontal posture along bottom surfaces 1Cof secondary batteries 1. In the four bind bars 4C at four cornerportions of the battery stack 5, the body portions 41 are disposed onboth sides of the battery stack 5 to prevent the horizontal movement ofthe secondary batteries 1, and the horizontal portions 43 are disposedon the upper and lower sides of the battery stack 5 to prevent theup-down movement of the secondary batteries 1.

Fourth Embodiment

Bind bars 40D illustrated in FIG. 11 each have an angular U-shaped crosssection defined by horizontal portions 43 at upper ends and lower endsof body portions 41 covering the entire side surfaces of the batterystack 5 to cover an upper surface and a lower surface of the batterystack 5. In the bind bars 40D, the body portions 41 and the horizontalportions 43 at the upper ends of the body portions 41 constituteprotective cover portions 8 that cover upper end corner portions 1T ofsecondary batteries 1. That is, the body portions 41 covering the sidesurfaces of the battery stack 5 function as side-surface covering parts8B of the protective cover portions 8, and the horizontal portions 43covering the upper surface of the battery stack 5 function asupper-surface covering parts 8A of the protective cover portions 8. Inthe bind bars 40D having this structure, the body portions 41 opposed tothe side surfaces of the battery stack 5 are made wide, and this canincrease the mechanical strength. Moreover, the body portions 41 coverthe entire side surfaces of the battery stack 5, and this can reliablyprevent scattering of the spark toward the side surfaces of the batterystack 5. In the bind bars 40D disposed on both side surfaces of thebattery stack 5 and having the angular U-shaped cross section, the bodyportions 41 are disposed on both sides of the battery stack 5 to preventhorizontal movement of the secondary batteries 1 and the horizontalportions 43 are disposed on the upper and lower sides of the batterystack 5 to prevent up-down movement of the secondary batteries 1.

Fifth and Sixth Embodiments

Further, in the binding members 4, the body portions 41 covering theside surfaces of the battery stack 5 can have open windows. In bind bars40E and 40F illustrated in FIGS. 12 and 13, body portions 41 coveringside surfaces of a battery stack 5 have open windows 44 in centerportions thereof. The illustrated open windows 44 are open to be opposedto intermediate portions of the side surfaces of the battery stack 5except for upper portions and lower portions.

In the bind bars 40E of FIG. 10, connecting pieces 42 are provided atboth ends of each of the body portions 41 having the open windows 44 inthe center portions, and horizontal portions 43 covering the uppersurface of the battery stack are provided at upper ends of the bodyportions 41. In the bind bars 40E, the body portions 41 areframe-shaped, and upper parts of the body portions 41 and the horizontalportions 43 function as protective cover portions 8 that cover upper endcorner portions 1T of secondary batteries 1.

In the bind bars 40F of FIG. 11, connecting pieces 42 are provided atboth ends of each of the body portions 41 having the open windows 44 incenter portions thereof, and horizontal portions 43 covering an uppersurface and a lower end of the battery stack are provided at upper endsand lower ends of the body portions 41. In the bind bars 40F, the bodyportions 41 are also frame-shaped, and upper parts of the body portions41 and the horizontal portions 43 at the upper ends function asprotective cover portions 8 that cover upper end corner portions 1T ofsecondary batteries 1.

Since these bind bars 40E and 40F have the open windows 44, the weightand cost of the bind bars 40E and 40F are reduced. Further, heat can beefficiently dissipated from the secondary batteries by exposing the sidesurfaces of the battery stack from the open windows 44. Although notillustrated, in particular, in an air-cooled power supply device thatcools secondary batteries by forcibly blowing cooling air between thesecondary batteries, the cooling air can be passed and blown through theopen windows provided as ventilations in the bind bars.

The above-described power supply devices can be used as avehicle-mounted power supply. As vehicles in which the power supplydevice is mounted, electrically driven vehicles, such as a hybrid carand a plug-in hybrid car that run by using both an engine and a motorand an electric car that runs by using only a motor can be used. Thepower supply device is used as a power supply for these vehicles.

The embodiments and examples of the present invention have beendescribed above with reference to the drawings. However, theabove-described embodiments and examples are just illustrative examplesfor embodying the technical idea of the present invention, and thepresent, invention is not limited to the above embodiments and examples.This description does not specify the members in the scope of the claimsto the members in the embodiments. In the above description, the samenames and symbols denote the same or equivalent members, and detaileddescriptions thereof are appropriately omitted. Further, in the elementsthat constitute the present invention, a plurality of elements may beconstituted by the same member so that one member functions as aplurality of elements. Conversely, the function of one member may beshared and realized by a plurality of members.

INDUSTRIAL APPLICABILITY

The power supply device and the vehicle including the power supplydevice according to the present invention can be suitably used as apower supply device for, for example, a plug-in hybrid electric car anda hybrid electric car capable of switching an EV running mode and an HEVrunning mode and an electric car. The power supply device can beappropriately used for applications as a backup power supply devicemountable in a computer server rack, a backup power supply device for awireless base station of, for example, a mobile phone, a power storagedevice used in combination with a solar battery, such as a domestic orfactory storage power supply or a power supply of a street light, and abackup power supply of a traffic light.

REFERENCE SIGNS LIST

-   100 power supply device-   1 secondary battery-   1A upper surface-   1B side surface-   1C bottom surface-   1X principal surface-   1T upper end corner portion-   2 separator-   3 end plate-   4 binding member-   5 battery stack-   6 bus bar-   7 current interrupt device-   8 protective cover portion-   8A upper-surface covering part-   8B side-surface covering part-   10 assembled battery-   11 outer can-   12 sealing plate-   12A short-circuit hole-   13 electrode terminal-   13A first electrode terminal-   13B second electrode terminal-   14 gas discharge valve-   15 electrode body-   16 collector member-   16A platelike portion-   17 gasket-   18 fixed member-   19 liquid injection portion-   20 short-circuit part-   21 fuse part-   21A fuse hole-   21B connecting portion-   22 inverting plate-   23 connection plate-   24 insulating portion-   25 welded portion-   45 insulating member-   40, 40A, 40B, 40C, 40D, 40E, 40F bind bar-   40X upper bind bar-   40Y, 40Z lower bind bar-   41 body portion-   42 connecting piece-   43 horizontal portion-   44 open window-   45 insulating member-   70 outer case-   71 lower case-   72 upper case-   73 end face plate-   74 flange-   101 secondary battery-   111 outer can-   112 sealing plate-   115 electrode body-   116 collector plate-   121 fuse part-   122 inverting plate-   123 connection plate-   124 insulating member

1. A power supply device comprising: a battery stack in which aplurality of secondary batteries are stacked; and a binding member thatbinds the battery stack, wherein each of the secondary batteriesincludes an electrode body having a positive electrode and a negativeelectrode, an outer can having an opening and shaped like a bottomedcylinder to contain the electrode body, a sealing plate that closes theopening of the outer can, a pair of electrode terminals disposed on thesealing plate, and a current interrupt device, wherein the pair ofelectrode terminals include a first electrode terminal insulated fromthe sealing plate and a second electrode terminal electrically connectedto the sealing plate, and are electrically connected to the electrodebody through a collector member inside the secondary battery, whereinthe current interrupt device includes a short-circuit part thatshort-circuits the first electrode terminal and the sealing plate whenan internal pressure of the secondary battery exceeds a set pressure,and a &se part provided in the collector member. wherein the fuse partis disposed close to an upper end corner portion as a boundary portionbetween an upper surface Mid a side surface of the secondary battery,and is fused by an overcurrent in a short-circuit state of theshort-circuit part, wherein the binding member includes a protectivecover portion located on each side of the battery stack to cover theupper end corner portion of the secondary battery, and wherein theprotective cover portion includes an upper-surface covering part thatcovers an upper surface of the upper end corner portion and aside-surface covering part that covers a side surface of the upper endcorner portion.
 2. The power supply device according to claim 1, whereinthe binding member is a bind bar formed by bending a metal plate havinga predetermined thickness.
 3. The power supply device according to claim2, wherein an insulating member is provided on an inner surface of thebind bar.
 4. The power supply device according to claim 2, wherein thebind bar includes an upper bind bar that covers an upper portion of aside surface of the battery stack and a lower bind bar that covers alower portion of the side surface of the battery stack, and wherein theupper bind bar also functions as the protective cover portion.
 5. Thepower supply device according to claim 2, wherein the bind bar has abody portion opposed to a side surface of the battery stack, and thebody portion covers the entire side surface of the battery stack.
 6. Thepower supply device according to claim 2, wherein the bind bar has abody portion opposed to a side surface of the battery stack, and thebody portion has an open window.
 7. The power supply device according toclaim 2, wherein the bind bar has a horizontal portion that covers atleast a part of a bottom surface of the battery stack.
 8. A vehiclecomprising the power supply device according to claim 1.